In a communications transmitter, information may be modulated onto orthogonal signals known as in-phase (I) and quadrature (Q) carriers to form I and Q channels. At the receiver, the I and Q channels may be demodulated to recover the information of interest. Typically, a mixer is provided to modulate or demodulate each channel, i.e., an I mixer for the I channel, and a Q mixer for the Q channel.
Accurate transmission and reception of information requires that the I and Q channels remain orthogonal to each other over the communications link. In practice, mismatch between the I and Q channels, e.g., the mixers of the I and Q channels at either the transmitter or the receiver, introduces correlation between the I and Q channels, causing information from the I channel to “bleed” into the Q channel, and vice versa. This leads to corruption of the information signals.
It would be desirable to provide techniques for reducing mismatch between the I and Q channels.